48 Mr Laurie, On Vehicles used by [Feb. 24, 



(3) On the origin of the embryos, in the ovicells of Cyclosto- 

 matous Polyzoa. By S. F. Harmer, M.A., King's College. 



[Reprinted from the Cambridge University Reporter, February 18, 1890.] 



The species investigated belonged to the genus Crisia, in which, 

 as in other forms of Cyclostomata, the mature ovicells contain a large 

 number of embryos. These embryos are imbedded in the meshes 

 of a nucleated protoplasmic reticulum, which also contains a mass 

 of indifferent cells, produced into finger-shaped processes, the free 

 ends of which are from time to time constricted off as embryos. 

 The embryos have, at this stage, a structure identical with that of 

 the youngest embryos described by previous authors. After de- 

 veloping various organs, they escape as free larvae through the 

 tubular aperture of the ovicell. The budding organ from which 

 the embryos are formed makes its appearance at an early stage in 

 the development of the ovicell. Evidence was brought forward to 

 show that it must be regarded as an embryo, produced from an 

 ovum. The supposed ovum is found in very young ovicells, im- 

 bedded in a compact follicle, and appears to give rise, by a remark- 

 able process of development, to the budding organ above described. 

 The embryos are thus produced by the repeated fission of a primary 

 embryo developed in the ordinary way from an egg. 



February 24, 1890. 

 Mr J. W. Clark, President, in the Chair. 

 The following were elected Fellows of the Society : 



A. P. Laurie, M.A., Fellow of King's College. 

 W. H. Young, M.A., Fellow of Peterhouse. 

 C. Platts, M.A., Fellow of Trinity College. 

 A. C. Seward, M.A., St John's College. 



The following Communications were made to the Society : 



(1) Vehicles used by the old Masters in Painting. Part I. 

 By A. P. Laurie, M.A., King's College. 



I have been engaged for some time in studying the methods 

 of painting used by the old masters, with a view to showing light 

 on the question why modern pictures are so far from permanent. 

 Fortunately a good deal of material exists for this enquiry, MSS. 

 having been left containing receipts for the preparation of oils, 

 colours and varnishes, and directions for using the same. More- 

 over these MSS. have been carefully edited and translated, and 



